The surface panels on the ball of this type each comprise a sheet material, and an elastic member such as foamed material laminated to the sheet material on its back side to provide flexibility of the ball. Each surface panel is cut into a predetermined shape and the outer peripheral edge of the surface panel is inwardly bent by a forming process. The surface panels are adhered to the peripheral surface of the body and furthermore, the bent portions of the adjacent surface panels are also adhered on their side faces to each other to compensate for low peeling resistance of the elastic material from the body. However, it has been known in the art that the perfect adhesion of the side faces of the bent portions of the adjacent surface panels to each other is difficult, and in particular, in the case where pentagonal and hexagonal panels are combined on the body to fabricate a ball, adhesion of the bent portion side faces of the surface panels to each other is so difficult at points of intersection of the surface panels that the portions of the surface panels adjacent the points of intersection peel off. When an impact is exerted on the adhered bent portions of the adjacent surface panels in a radial direction towards the center of the sphere, weak adhesion results in destruction of the portions of the adjacent surface panels or release of the surface panels from the body.
It has been proposed that in order to increase surface area of the side faces of the bent portions of the adjacent surface panels, the peripheral edge portion of each of the surface panels is bent at about 90 degrees. This requires formation of slits or slots in or removal the portions of an elastic member adjacent the outer peripheral edge of the surface panel to facilitate bending the peripheral edge of the surface panel (refer to patent document 1). This has the disadvantage of decreasing strength of the portions of the elastic member adjacent the peripheral edge of the surface panel so that the adhesion of the elastic member to the body becomes weaker.
In addition, strength of adhesion of the adjacent surface panels to each other on their sides increases, but there is the disadvantage in that the flexibility of the ball is lost. Furthermore, since grooves at a seam of the adjacent surface panels become shallower, the trajectory of the ball's flight exhibits a behavior close to an aerodynamic character of a sphere having a smooth surface. For example, when reaching some speed, the trajectory of ball flight rapidly varies and exhibits a so-called abnormal movement.
Unlike the ball as described above, it has been proposed heretofore to define a groove at a seam of the adjacent surface panels attaching importance to the aerodynamic character. This is achieved by arching the peripheral edge portion of each of adjacent surface panels and adhering only the surface panels to a body without adhering the arched portions of the surface panels to each other (refer to patent document 2). With this arrangement, however, there is danger of the surface panels peeling from the ball body unless a high strength of adhesion is provided.    Patent document 1: Patent Application Publication 2009-254636    Patent document 2: Patent Application Publication 2010-240427